This publication constitutes essential reading for academics, teachers and language policy makers wanting to understand, plan, and implement an educational language program involving learner mobility. The book provides data and analyses from a long-term program of research on study abroad (the SALA Project), which looked into the short and long-term effects of instructional and mobility contexts on language and cultural development from two perspectives: the participants’ language acquisition development over 2,5 years, and the practitioners’ perspective in relation to the design and implementation of a mobility program. The book is innovative in the longitudinal data it offers, the light it sheds on (i) an array of language skills, both productive and receptive, oral and written, tapping into phonology, lexis, grammar and discourse, (ii) the role of individual differences (including attitudes, motivation, beliefs, and intercultural awareness), and (iii) the insights on the effects of length of stay. This book represents an addition to previous research on the outcomes of mobility policies to promote L2 learners’ linguistic development and the individual and educational conditions that appear to facilitate success in study abroad programs.